Photovoltaic power station refers to a photovoltaic power generation system that uses solar energy and uses special materials such as crystalline silicon panels, inverters and other electronic components to connect to the grid and transmit electricity to the grid. Among them, photovoltaic power stations can be divided into centralized photovoltaic power stations and distributed photovoltaic power stations. So what is the difference between centralized photovoltaic power stations and distributed photovoltaic power stations? Let’s take a look at it together.
Characteristics of distributed photovoltaic power plants
The basic principle of distribution: mainly based on the surface of the building, solve the user's power consumption problem nearby, and realize the compensation and delivery of the power supply difference through the grid connection.
1. Advantages of distributed photovoltaic power plants:
1. The photovoltaic power source is on the user side, and the power generation supplies the local load, which is regarded as the load, which can effectively reduce the dependence on the power grid and reduce the line loss.
2. By making full use of the building surface, photovoltaic cells can be used as building materials at the same time, effectively reducing the floor space of photovoltaic power plants.
3. Effective interface with smart grid and micro grid, flexible operation, and independent operation of off-script grid under appropriate conditions.
2. Disadvantages of distributed photovoltaic power station:
1. The direction of the power flow in the distribution network will change in time, the reverse flow will cause additional losses, the related protections need to be re-adjusted, and the transformer taps need to be constantly changed.
2. Difficulties in voltage and reactive power regulation. There are technical difficulties in the control of power factor after the connection of large-capacity photovoltaics, and short-circuit power will also increase.
3. An energy management system at the distribution grid level is required to perform the same management of loads in the case of large-scale photovoltaic access. New requirements are provided for secondary equipment and communications, increasing the complexity of the system.
Features of Centralized Photovoltaic Power Plants
The basic principle of centralization: make full use of the abundant and relatively stable solar energy resources in desert areas to build large-scale photovoltaic power stations, and connect to high-voltage transmission systems to supply long-distance loads.
1. Advantages of centralized photovoltaic power station:
1. Due to the more flexible location selection, the stability of photovoltaic output has increased, and the positive peak shaving characteristics of solar radiation and electricity load are fully utilized to play a role in peak shaving.
2. The operation mode is more flexible. Compared with distributed photovoltaics, it is more convenient to control reactive power and voltage, and it is easier to participate in grid frequency adjustment.
3. The construction period is short, the environmental adaptability is strong, no raw material guarantees such as water source and coal-fired transportation are not required, the operation cost is low, it is convenient for centralized management, and the capacity is easily realized due to the small limitation of space.
2. Disadvantages of centralized photovoltaic power station:
1. It is necessary to rely on long-distance transmission lines to transmit power into the grid, and at the same time, it is also a large source of interference to the grid, and problems such as loss of transmission lines, voltage drops, and reactive power compensation will become prominent.
2. The large-capacity photovoltaic power station is realized by the combination of multiple conversion devices. The coordinated work of these devices needs to be managed in a unified manner. At present, the technology in this area is still immature.
3. In order to ensure the safety of the power grid, large-capacity centralized photovoltaic access requires new functions such as LVRT, which often conflict with isolated islands.
The centralized large-scale grid-connected photovoltaic power station is the country's utilization of the desert. It is recommended that the large-scale photovoltaic power station generate electricity directly into the public grid, and connect to the high-voltage transmission system to supply long-distance loads. Distributed small grid-connected photovoltaic systems, especially photovoltaic building-integrated power generation systems, are the mainstream of grid-connected photovoltaic power generation in developed countries due to the advantages of small investment, fast construction, small footprint, and strong policy support.